Brazil’s largest city was plunged into darkness in the middle of the day Monday as a massive plume of smoke from fires burning in the Amazon descended on the city, alarming residents as a record number of fires raged in the world’s largest tropical rainforest.

Day turned to night around 3 p.m., according to the Folha de S.Paulo newspaper, and persisted for more than an hour.

Officials with Brazil’s National Institute of Meteorology (Inmet) said the unnerving scene was the result of a combination of factors: cold, humid air, and smoke from unprecedented fires burning in the Amazon rainforest thousands of miles away.

“The particulate matter, coming from the smoke produced by these large wildfires that are happening in Bolivia, coupled with the cold, humid air that is off the coast of São Paulo, caused the darkness,” Franco Vilela, a meteorologist at Inmet, told Globo.

Josélia Pegorim, a meteorologist with Climatempo, explained that the cold front changed the direction of the winds and transported smoke billowing from fires in Bolivia in the Brazilian state of Rondônia to the region, resulting in a dense layer of low, heavy clouds and fog.

Atmospheric monitoring data from the World Meteorological Organization showed a massive smoke plume emanating from the rainforest fires had spread across Brazil and over the coastal area Tuesday.

From the other side of Earth, here’s the latest on the Amazonia fires 🌳

Produced by @CopernicusEU’s atmosphere monitoring service, it shows the smoke reaching the Atlantic coast and São Paulo 🇧🇷

DATA HERE▶️https://t.co/Q6qzFdPfIT

04:39 PM – 20 Aug 2019

The darkness caused many on social media to express concerns over ongoing fires burning in world’s largest tropical forest, which some have dubbed the “lungs of the planet.”

A record number of wildfires have torched the Amazon this year as deforestation efforts increase under far-right Brazilian President Jair Bolsonaro.

🌎Just a little alert to the world: the sky randomly turned dark today in São Paulo, and meteorologists believe it’s smoke from the fires burning *thousands* of kilometers away, in Rondônia or Paraguay. Imagine how much has to be burning to create that much smoke(!). SOS🌎

02:04 AM – 20 Aug 2019

Brazil’s space research center, National Institute for Space Research (INPE), said Tuesday the number of fires detected in the Amazon so far this year had reached 72,843 — an 83% increase over the same period last year and the highest since the agency began recording the data in 2013, according to Reuters.

Meanwhile, deforestation of the Amazon soared by about 67% through July of this year, according to preliminary data reported by the INPE.

NOAA

Smoke from fires in the Amazon is seen from satellite Aug. 12.

Bolsonaro, who vowed to develop the Amazon region when he took office in January, has criticized the government agency’s data and recently fired its head over what he called “lies” that damaged Brazil’s reputation.

“News like this that does not match the truth causes great damage to the image of Brazil,” Bolsonaro, referring to the deforestation numbers, claimed in a press conference.

Because of its natural moisture and humidity, the Amazon has historically been relatively fire-resistant, according to NOAA. Wildfires occurring in the tropical forest today are the result of human activity and droughts, the agency said.